1. Technical Field
The present invention relates to a liquid supply device for supplying liquid to a liquid ejecting portion, and a liquid ejecting apparatus equipped with the liquid supply device.
2. Related Art
As an example of a liquid ejecting apparatus that ejects liquid onto a medium, an ink jet type printer has been widely known. This printer carries out printing by causing ejecting nozzles, which are formed on a liquid ejecting head (a liquid ejecting portion), to eject ink (liquid), which is supplied from an ink cartridge (a liquid storage portion), onto a medium (a paper sheet, for example). In recent years, pigment ink, ultraviolet-ray curable ink (UV ink), or the like has been used in such a printer.
This type of ink contains sedimenting components (pigment particles, for example) that are higher in specific gravity than solvent of the ink and sedimented in the solvent. Therefore, the sedimenting components are sedimented in the solvent with the elapse of time, and thus the density of the sedimenting components becomes irregular. As a result, there is a problem in that hue of the ink changes. Particularly, it is easy for the sedimenting components to be sedimented in a liquid supply path that is an ink flow path extending from the ink cartridge to the liquid ejecting head. Therefore, if the irregularity in the density of the pigment particles, which is caused by the sedimentation, is not suppressed in the liquid supply path, it is difficult to suppress the change of the hue of the ink supplied to the liquid ejecting head, even when the ink of which pigment particles are agitated is supplied from the ink cartridge through the liquid supply path, for example.
Accordingly, a technique that is capable of suppressing a change of hue of ink supplied to a liquid ejecting head has been proposed in JP-A-2011-98537, for example. In this technique, time measurement starts after the liquid ejecting head discharges ink supplied from a liquid supply path (a liquid passage), and further, a low flow velocity time, namely the time in which the ink flow velocity in the liquid supply path does not attain the predetermined flow velocity, is obtained. Then, the ink is discharged from the liquid ejecting head, by referring to the obtained low flow velocity time, to allow the ink in the liquid supply path to flow.
Meanwhile, regarding ink, such as pigment ink or UV ink, the viscosity coefficient of solvent thereof varies with a temperature change. Thus, in the case of ink of which the viscosity at low temperature is higher than that at high temperature, if the temperature of the ink lowers, the sedimentation velocity of sedimenting components in the solvent is reduced. Thus, if the discharging ink through the liquid ejecting head is carried out only based on a time measurement result of the low flow velocity time, it can cause the following problem. When the temperature of the ink lowers, for example, there is a possibility that the ink is discharged outside the liquid supply path even when the sedimenting components are not too much sedimented. As a result, an ink flowing operation is performed more than necessary in the liquid supply path, and thus, the ink can be wasted unnecessarily or energy (electric power, for example) can be wasted unnecessarily for the flowing operation.
Such a situation is usually common in a liquid supply device that includes a liquid storage portion for storing, not limited to ink, liquid containing sedimenting components and a liquid supply path which extends from the liquid storage portion to a liquid ejecting portion and through which the liquid to be supplied to the liquid ejecting portion can flow, and a liquid ejecting apparatus equipped with this liquid supply device.